Light emitting diodes (LEDs) have been utilized since about the 1960s. However, for the first few decades of use, the relatively low light output and narrow range of colored illumination limited the LED utilization role to specialized applications (e.g., indicator lamps). As light output improved, LED utilization within other lighting systems, such as within LED “EXIT” signs and LED traffic signals, began to increase. Over the last several years, the white light output capacity of LEDs has more than tripled, thereby allowing the LED to become the lighting solution of choice for a wide range of lighting solutions.
LEDs exhibit significantly optimized characteristics, such as source efficacy, optical control and extremely long operating life, which make them excellent choices for general lighting applications. LED efficiencies, for example, may provide light output magnitudes up to 200 lumens per watt of power. Energy savings may, therefore, be realized when utilizing LED-based lighting systems as compared to the energy usage of, for example, incandescent, halogen, compact fluorescent and high-intensity discharge (HID) lighting systems. As per an example, an LED-based lighting fixture may utilize a small percentage (e.g., 15-20%) of the power utilized by a halogen-based lighting system, but may still produce an equivalent magnitude of light.
While HID lighting systems have been the predominant choice for conventional horticultural lighting applications, LED technologies are gaining attraction due to their high luminous efficacy and their ability to produce narrow-band spectral distributions. Current LED-based horticultural lighting systems, however, fail to produce adequate light uniformity for indoor horticulture facility applications where natural light is not present nor do they produce adaptable spectral tuning. In addition, conventional LED-based horticultural lighting systems produce light rays exhibiting decreased intensity with increasing emission angle relative to the optical axis. Accordingly, none of the control systems used to effect adequate light distribution characteristics, spectral tuning and power efficiency are in existence either.
Efforts continue, therefore, to develop an LED lighting system and associated controls that exceed the performance parameters of conventional horticultural lighting systems.